Medicaments are prescribed in specific quantities or doses. For a medicament that is not in the form of a tablet or capsule the patient must be responsible for metering the dose. When the medicament is a liquid the specific dose is not as difficult to measure since the dosing is usually by means of a dropper, teaspoon or the use of dosing markings on a bottle cap. Such amounts are not quantitatively reproducible but may be accepted as marginally satisfactory. Syringe dispensers provide more acceptable results, but are only practical for small quantities, i.e., less than twenty milliliters. These methods of measurement are not easily accommodated for solids such as powders and granular materials. Powders may be light and can escape during transfer while granular materials often flow too freely and spill over the rim of the measuring container. If the materials are tamped or compressed into a teaspoon or bottle cap the quantity may easily be altered and leveling the top causes losses. Filling a cap up to a specific mark does not provide an acceptable means of dispensing either a liquid or a solid when the specific dose is essential.
Few devices have been developed to dispense metered quantities of powders. In U.S. Pat. No. 5,243,970 Ambrosio et al. teaches a device to administer metered amounts of powdered medicaments. The device is complex and moves a powder from a reservoir to a metering plate having a series of openings or perforated areas. A blade assembly scrapes the powder into the perforated areas. Spring loaded means rotate the plate. The medicament is administered by inhalation through a conduit. The dose is the quantity of powder that is scraped into one set of perforated areas. The doses dispensed from this device are extremely small. McDerment, in U.S. Pat. No. 6,176,238 teaches a dispenser for substances in powder or granular form. The dose of powder is moved from a reservoir vertically downward to a disc having a metering hole. The powder is then inhaled by mouth through a mouthpiece affixed at the bottom of the device. The device must be vertical when the powder enters the metering hole. To insure that the device is properly held, a mechanism is provided insuring that no powder is dispensed unless the device is in a vertical orientation. The dose dispensed by this device is also very small being only that quantity that is contained in the metering hole.
Devices have been developed to dispense measured quantities of solids such as coffee, sugar, salt, powdered milk or soap powder. These devices are affixed to the container holding the particular solid. When the container is a jar the dispensing device can replace the screw cap on the jar. If the container is a box, the device is usually attached to the box adjacent to a pouring opening on the side or top of the box. Partitions within the devices create two areas, one as a filling area and the other as a dispensing area. The container with the device attached is inverted a first time to permit the powder to enter the filling area, a second time to permit the powder to enter the dispensing area, and a third time to allow the powder to flow out of the device through a discharge opening. The filling area is usually refilled during last step so that once the first dispensing has been completed there is always powder in the filling area. These devices can dispense measured quantities of powder, but even with a dispensing area of a specific volume, the third inversion cannot prevent material in the filling area from spilling over the partition into the dispensing area. These devices are inexact and as noted are not meant for medicaments. (U.S. Pat. No. 2,243,452 to Bickel et al.; U.S. Pat. No. 2,853,213 to Buehlig; U.S. Pat. No. 2,899,115 to Matter; and U.S. Pat. No. 3,687,341 to Stanley et al.) Joy, in U.S. Pat. No. 4,144,989 adds an adjustable baffle to a similar arrangement of partitions as noted above. The adjustable baffle varies the size of the measuring area, but does not produce exact quantities and has questionable reproducibility. The quantities of powder dispensed through these devices are, for the most part, considerably greater than would be desired for a medicament so that acceptable tolerances can be considerably larger.
Another form of measuring dispenser is designed for dispensing powdered milk and is taught by Liu in U.S. Pat. No. 5,588,563. A cylinder containing the powder is fitted with a metering cap. The cap has a transparent or translucent cover marked off in metered lines. A plate separates the container from the interior of the cap and has an opening to permit the powder to flow from the container into the cap when the cylinder is inverted. A rotatable divider enables changing the quantity of powder dispensed by noting the position of the divider through the transparent cover. The cap is filled with the desired quantity of powder and an outlet in the cover is opened so the powder can be poured out. This device could not dispense exact quantities determined to minimal tolerances.
None of the aforementioned powder dispensing devices can dispense reproducible quantitative amounts of material nor do they provide any form of seal between the container of material and the dispenser when material is being stored with the measuring device attached to the container. None of these devices provide for sealing means to exclude moisture from the dispenser or container.
There is a need for a device to dispense quantitatively measured doses of a powdered or granular medicament as well as a liquid with minimal tolerances. There is a need for such a device that can easily be used by the young, the elderly and persons with limited dexterity and visual impairments as well as by the able-bodied. There is also a need for a device that does not become clogged, does not admit moisture, and provides a seal to close off the reservoir from the dispensing chamber so material does not move from the reservoir into the dispensing chamber when the dose is dispensed. There is a need for a dispensing device that has sealing means to separate the reservoir from the atmosphere so that it does not have to be separated from the reservoir when the dispenser is not in use.